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    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
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<body>
    <script>
        function Fn() {
            this.x = 100;
            this.y = 200;
            this.getX = function () {
                console.log(this.x);
            }
        }
        Fn.prototype.getX = function () {
            console.log(this.x);
        };
        Fn.prototype.getY = function () {
            console.log(this.y);
        };
        let f1 = new Fn;
        let f2 = new Fn;
     
        console.log(f1.getX === f2.getX); //false
        console.log(f1.getY === f2.getY); //true
        console.log(f1.__proto__.getY === Fn.prototype.getY); //true
        console.log(f1.__proto__.getX === f2.getX); //false
        console.log(f1.getX === Fn.prototype.getX); //false
        console.log(f1.constructor); //Fn
        console.log(Fn.prototype.__proto__.constructor); //Object

    </script>
</body>
</html>